Comprehensive Study Notes for NPTE - Neuromuscular and Cerebrovascular Topics
Upper Motor Neuron (UMN) vs Lower Motor Neuron (LMN)
Characteristics:
Location:
UMN: Found in the CNS, above the anterior horn cell, including the cerebral cortex, brainstem, and spinal cord tracts.
LMN: Found in the PNS, at or below the anterior horn cell, including cranial nerve nuclei/axons and anterior horn cells/spinal roots/peripheral nerves in the spinal cord.
Structures:
UMN:
Cortex (precentral gyrus, motor cortex)
Brainstem (descending tracts)
Spinal Cord (descending tracts like corticospinal tract, rubrospinal tract)
Corticospinal tract (lateral and anterior)
LMN:
Cranial Nerves (CN): Cranial nuclei in brainstem and their peripheral axons
SC: Anterior horn cells, spinal roots, peripheral nerves
Neuromuscular junction (NMJ)
Muscle fibers
Disorders:
UMN:
CVA (Cerebrovascular Accident)
TBI (Traumatic Brain Injury)
SCI (Spinal Cord Injury), especially above the conus medullaris
MS (Multiple Sclerosis)
Cerebral Palsy
Huntington's Disease (some UMN involvement)
LMN:
Peripheral neuropathy (e.g., Diabetic neuropathy)
Radiculopathy (nerve root compression)
Poliovirus (affects anterior horn cells)
GBS (Guillain–Barré Syndrome)
Myasthenia Gravis (NMJ disorder)
Bell's Palsy (facial nerve LMN lesion)
Carpal Tunnel Syndrome (median nerve entrapment)
Tone:
UMN:
Hypertonic; velocity-dependent (spastic), presenting as increased resistance to passive movement, often resulting in a clasp-knife phenomenon.
In acute injury, decreased tone may be observed due to spinal shock (in SCI) or cerebral shock (in CVA), which can last for days to weeks.
Note: To assess spasticity, use the modified Ashworth scale, which grades resistance from (no increase in tone) to (rigid in flexion or extension).
LMN:
Hypotonic (decreased tone), leading to muscle weakness and reduced resistance to passive movement; flaccid (absent tone) means complete loss of tone; not velocity-dependent.
Reflexes:
UMN:
Hyperreflexia: increased deep tendon reflexes (DTRs), often clonus and exaggerated responses.
Clonus: maintained stretch leading to cyclical contractions (e.g., ankle plantar flexion and wrist flexion), usually >5 beats is pathological.
Positive Babinski sign: toes extended and fanned out (dorsiflexion of the great toe and fanning of other toes) is indicative of UMN lesion in adults (primitive spinal reflex persistence).
Loss of superficial reflexes (e.g., abdominal, cremasteric).
LMN:
Hyporeflexia: decreased DTRs, ranging from diminished to absent (areflexia).
Normal or absent superficial reflexes.
Involuntary Movement:
UMN:
Muscle spasms or spasticity: involuntary contractions affecting either flexors or extensors, contributing to abnormal posturing.
Denervation may lead to fasciculations in some chronic UMN lesions if anterior horn cells also degenerate (e.g., ALS).
LMN:
May experience fasciculations (visible, spontaneous contractions of a fascicle of muscle fibers) and fibrillations (spontaneous, fine contractions of single muscle fibers, not visible and only detected by EMG) due to denervation.
Muscle Bulk:
UMN:
Disuse atrophy: mild to moderate muscle wasting due to lack of voluntary use, but not as profound as LMN lesions.
LMN:
Marked neurogenic atrophy: severe and rapid muscle wasting due to denervation, often visible within weeks.
Strength:
UMN:
Weakness in all muscle groups supplied by the affected tract; often presented in patterned weakness (e.g., flexor synergy in upper extremity, extensor synergy in lower extremity).
CVA: weakness or paralysis on one side of the body (hemiparesis/hemiplegia), typically contralateral to the lesion in the brain due to decussation of corticospinal tracts.
SCI: weakness or paralysis consistent with the injury's location and completeness, can be unilateral or bilateral (paraplegia, tetraplegia).
Corticospinal tract injury yields contralateral weakness if above the medulla and ipsilateral if below (e.g., spinal cord lesion).
LMN:
Specific strength loss corresponding to the nerve or nerve roots impaired, affecting precise muscles or myotomes.
Radiculopathy: specific myotome weakness (e.g., C5 weakness in shoulder abduction).
Polyneuropathy: weakness initially distal and symmetrical (glove-and-stocking pattern), progressing to proximal muscle groups.
Mononeuropathy: specific muscle weakness from a single nerve entrapment or injury (e.g., wrist drop from radial nerve injury).
Note: Myopathies typically show proximal muscle weakness (e.g., difficulty rising from a chair) while neuropathies show distal muscle weakness (e.g., foot drop).
Cranial Nerves (CN)
Mnemonics:
CN locations: “CE MI PONS MEDU”
CN I and II: CErebrum (2 letters)
CN III and IV: MIdbrain (2 letters)
CN V, VI, VII, VIII: PONS (4 letters)
CN IX, X, XI, XII: MEDUlla (4 letters)
CN type (Sensory, Motor, Both): “Some Say Marry Money But My Brother Says Big Brains Matter More”
Individual Cranial Nerves and Functions:
Olfactory (CN I): Sensory – Smell.
Optic (CN II): Sensory – Vision.
Oculomotor (CN III): Motor – Eye movement (up, down, medial), pupillary constriction, eyelid elevation.
Trochlear (CN IV): Motor – Eye movement (down and in).
Trigeminal (CN V): Both – Sensory for face, scalp, teeth; Motor for mastication (chewing muscles).
Abducens (CN VI): Motor – Eye movement (lateral).
Facial (CN VII): Both – Motor for facial expression, lacrimation, salivation; Sensory for taste (anterior of tongue).
Vestibulocochlear (CN VIII): Sensory – Hearing and balance.
Glossopharyngeal (CN IX): Both – Motor for swallowing, salivation; Sensory for taste (posterior of tongue), pharynx sensation, carotid body/sinus reflexes.
Vagus (CN X): Both – Motor for swallowing, speaking (larynx), parasympathetic innervation to viscera; Sensory for taste, pharynx, larynx, and thoracic/abdominal viscera.
Accessory (CN XI): Motor – Shoulder shrug (trapezius), head turning (sternocleidomastoid).
Hypoglossal (CN XII): Motor – Tongue movement.
Differential Diagnosis of CNS Disorders
Location of Lesion: Specific neurological signs depend heavily on the anatomical location of the damage.
Cerebral Cortex: (e.g., CVA, tumor, trauma)
Disorder: CVA, Traumatic Brain Injury (TBI), cortical tumors.
Sensation: Decreased contralateral sensation (hemianesthesia) depending on location (e.g., parietal lobe).
Tone: Hypertonia, spasticity (velocity-dependent), often with a clasp-knife effect due to UMN damage.
Reflexes: Increased DTRs (hyperreflexia), positive Babinski sign, clonus.
Strength: Contralateral weakness or paralysis (hemiparesis/hemiplegia), often affecting distal muscles more.
Other signs: Cognitive deficits (aphasia, apraxia, neglect), visual field deficits, seizures.
Basal Ganglia: (e.g., Parkinson’s disease, Huntington’s disease)
Disorder: Parkinson’s disease, Huntington’s disease, Dystonia, Tourette's Syndrome.
Sensation: Generally normal, although some patients may report decreased sensation.
Tone: Either normal or increased (rigidity), which is non-velocity-dependent (lead-pipe or cogwheel rigidity).
Reflexes: Normal or may be slightly weak, but typically not hyperreflexic.
Strength: Normal or weak; specific weaknesses leading to bradykinesia (slow movement), akinesia (difficulty initiating movement), or hypokinesia (reduced movement amplitude).
Other signs: Tremors (resting tremor in PD), chorea (involuntary, jerky movements in HD), athetosis (slow, writhing movements), dystonia (sustained muscle contractions causing twisting and repetitive movements).
Cerebellum: (e.g., tumor, CVA, ataxia)
Disorder: Cerebellar lesion (e.g., tumor, CVA, MS, hereditary ataxias, chronic alcoholism).
Sensation: Normal.
Tone: Often hypotonia (decreased muscle tone).
Reflexes: Normal or pendular reflexes.
Strength: Normal individual muscle strength, but impaired coordination leading to ataxia, dysmetria, dysdiadochokinesia, and dyssynergia.
Other signs: Intention tremor (tremor during voluntary movement), nystagmus (involuntary eye movements), dysarthria (scanning speech), impaired balance and gait (wide base of support, unsteady).
Spinal Cord: (e.g., SCI, MS, tumor)
Disorder: SCI (complete or incomplete trauma), Transverse Myelitis, Spinal Stenosis, tumors, MS affecting spinal tracts.
Sensation: Decreased or absent sensation below the level of the lesion, depending on the tracts affected (e.g., spinothalamic, dorsal column).
Tone: Changeable; initially flaccid below the lesion due to spinal shock (if acute), then often spastic (hypertonic) due to UMN damage.
Reflexes: Areflexia during spinal shock, then hyperreflexia below the level of the lesion (if UMN pathways are compromised).
Strength: Decreased or absent strength (paresis/paralysis) below the level of the lesion.
Muscle bulk affected: Can show disuse atrophy below lesion; if anterior horn cells or nerve roots are damaged at the level of the lesion, LMN signs (flaccidity, atrophy, fasciculations) may be present at that specific segment.
Other signs: Autonomic dysreflexia (in SCI above T6), bowel/bladder dysfunction, sexual dysfunction.
Degenerative Disorders
Multiple Sclerosis (MS)
Characteristics:
Autoimmune disease marked by chronic, progressive demyelination of the CNS, focusing on UMNs, but can also affect sensory and cerebellar pathways.
Commonly affects white females aged 20-40, likely with a viral etiology (e.g., Epstein-Barr virus) and genetic predisposition.
Under normal conditions, oligodendrocytes produce myelin to insulate nerves for energy conservation through saltatory conduction, allowing for rapid signal transmission.
With MS, immune-mediated myelin destruction leads to diminished energy conservation and slowing of nerve impulses, suggesting demyelinating lesions (plaques) which slow neural transmission and increase the risk of fatigue, weakness, and sensory deficits. Axonal damage can also occur.
Signs/Symptoms (S/S):
Unilateral symptoms are common, but can be bilateral.
Optic symptoms:
Nystagmus (involuntary repetitive eye movements)
Optic neuritis (pain with eye movement and temporary vision loss in one eye)
Diplopia (double vision) due to extraocular muscle weakness or cranial nerve involvement
Marcus Gunn pupil (afferent pupillary defect, where affected pupil constricts less to direct light than to consensual light)
Systemic symptoms: Fatigue (most common and debilitating symptom), leading to muscle weakness and possible foot drop.
Motor symptoms: Spasticity, hyperreflexia, muscle weakness, abnormal gait, ataxia, intention tremors, dysmetria, and dyssynergia common due to cerebellar impact.
Sensory symptoms: Paresthesia (numbness, tingling), dysesthesia (burning, aching), hyperpathia (hypersensitivity to minor stimuli).
Pain: Neuropathic pain (e.g., Trigeminal neuralgia), Lhermitte sign (electrical shock sensation down the spinal cord when the neck is flexed).
Autonomic dysfunction: Bowel and bladder conditions (spastic bladder, flaccid bladder, dyssynergic bladder, constipation, urinary urgency/frequency).
Speech and Swallowing: Dysphasia and/or dysarthria (slow, slurred, or scanning speech).
Cognitive: Memory loss, attention deficits, slowed processing speed.
Affective: Pseudobulbar affect (uncontrollable laughter or crying), depression, anxiety.
Other: Uhthoff phenomenon (increased symptoms from heat exposure), fatigue after minimal exertion.
Diagnosis:
Evidence of damage must be present in 2 separate areas of the CNS at 2 different times (Dissemination in Space and Dissemination in Time) based on revised McDonald criteria.
MRI: Look for two or more lesions (plaques) in at least two of four CNS areas (periventricular, juxtacortical, infratentorial, spinal cord).
Spinal tap (lumbar puncture): Elevated immunoglobulin () levels and presence of oligoclonal bands (unique Ig bands not found in serum) in cerebrospinal fluid (CSF).
Evoked Potentials: Slowed conduction velocities in visual, auditory, or somatosensory pathways.
Types of MS:
Relapsing-remitting MS (RRMS): Characterized by clearly defined short-duration attacks (relapses) with full or partial recovery (remissions). Most common type (85%).
Primary progressive MS (PPMS): There is a steady, gradual decline of function from onset without distinct attacks or remissions.
Secondary progressive MS (SPMS): Initially relapsing-remitting, followed by a gradual and steady decline of function, with or without occasional relapses.
Progressive-relapsing MS (PRMS): Steady decline from onset with acute attacks layered on top (rarest type).
Medical Management:
Acute Relapses: Immunosuppressive drugs (IV corticosteroids like methylprednisolone, oral prednisone, dexamethasone) to treat acute flare-ups, shorten duration of episodes, and reduce inflammation.
Disease Modifying Therapies (DMTs): Interferon drugs (e.g., Avonex, Betaseron, Rebif), glatiramer acetate (Copaxone), and newer oral or infusion therapies (e.g., natalizumab, fingolimod) slow disease progression and reduce relapse frequency.
Symptom Management: Spasticity drugs (baclofen, tizanidine, diazepam) are used to reduce muscle stiffness. Urinary drugs (anticholinergic drugs like oxybutynin) to control incontinence. Amantadine for fatigue. Gabapentin/carbamazepine for neuropathic pain.
Physical Therapy Treatment:
Energy conservation and pacing strategies: Avoid fatigue and overheating (Uhthoff phenomenon); teach activity modification and rest breaks. Keep an activity diary to identify patterns.
Maintain optimal mobility: Incorporate flexibility exercises (addressing specific tight areas, e.g., hip flexors, hamstring), strengthening exercises (especially for anti-gravity muscles), and aerobic conditioning.
Spasticity management: Utilize appropriate muscle groups, stretching, modalities (e.g., cold packs), positioning schedules, and orthotics/splints.
Balance and gait training: Address ataxia, dysmetria, and use compensatory strategies, assistive devices (canes, walkers), and task-specific training. Emphasize core stability.
Patient education: Monitor for complications such as UTIs, respiratory infections, skin breakdown. Address safety in home and community.
Parkinson's Disease (PD)
Characteristics:
Chronic, progressive neurodegenerative disorder caused by the degeneration of dopamine-producing neurons in the substantia nigra of the basal ganglia, leading to a reduction in dopamine (a neurotransmitter crucial for motor control).
Affects movement, muscle control, and balance. Typically diagnosed in later life (average onset around 60 years).
Signs/Symptoms (S/S):
Cardinal symptoms (TRAP mnemonic):
Tremor: Resting tremor (often 'pill-rolling' tremor in hands), usually unilateral at onset.
Rigidity: Lead-pipe or cogwheel rigidity (non-velocity-dependent resistance to passive movement).
Akinesia/Bradykinesia: Difficulty initiating movement, slowness of movement, reduced amplitude of movement (e.g., micrographia, masked face, decreased arm swing).
Postural Instability: Impaired balance, leading to increased fall risk; stooped posture.
Other motor symptoms: Shuffling gait (festinating gait), freezing of gait, dysarthria (hypophonic speech), dysphagia, oculomotor dysfunction.
Non-motor symptoms: Cognitive impairment (dementia in later stages), depression, anxiety, sleep disturbances, olfactory dysfunction (loss of smell), autonomic dysfunction (orthostatic hypotension, constipation).
Diagnosis:
Primarily clinical, based on neurological examination and presence of cardinal motor symptoms. Response to levodopa can support diagnosis.
DaTscan (dopamine transporter scan) can help differentiate PD from essential tremor but is not routinely used for primary diagnosis.
Medical Management:
Levodopa (Sinemet): Primary medication, converted to dopamine in the brain, very effective but can lead to motor fluctuations and dyskinesias over time.
Dopamine agonists (pramipexole, ropinirole): Mimic dopamine effects, often used in early PD or as adjuncts to levodopa.
MAO-B inhibitors (selegiline, rasagiline): Prevent dopamine breakdown.
Amantadine: Reduces dyskinesias.
Deep Brain Stimulation (DBS): Surgical option for advanced PD with motor fluctuations, involves electrodes implanting in specific brain areas.
Physical Therapy Treatment:
Focus on improving mobility, balance, gait, and functional independence.
LSVT BIG (Lee Silverman Voice Treatment BIG): High-amplitude, exaggerated movements to counteract bradykinesia and hypokinesia.
Gait training: Use of external cues (visual, auditory), rhythmic initiation, increasing step length and arm swing, addressing freezing episodes.
Balance exercises: Challenge stability limits, incorporate dynamic balance activities, fall prevention education.
Flexibility and strengthening: Address rigidity and weakness through stretching and resistance exercises.
Patient education: Home exercise programs, energy conservation, safe transfers, adaptive equipment, dual-task training.
Amyotrophic Lateral Sclerosis (ALS)
Characteristics:
Progressive neurodegenerative disease that affects both UMNs (corticospinal tracts) and LMNs (anterior horn cells, cranial nerve nuclei), leading to muscle weakness, atrophy, and spasticity.
Sensation and cognition are typically spared, though some cognitive changes (e.g., frontotemporal dementia) can occur.
Rapidly progressive and fatal, with a median survival of 2-5 years from diagnosis.
Signs/Symptoms (S/S):
Mix of UMN and LMN signs:
LMN Signs: Muscle weakness and atrophy, fasciculations, hyporeflexia (initially, can become hyperreflexia later in affected areas), muscle cramps.
UMN Signs: Spasticity, hyperreflexia, presence of pathological reflexes (e.g., Babinski sign), clonus.
Bulbar onset: Dysarthria (slurred speech), dysphagia (difficulty swallowing), sialorrhea (excessive drooling), respiratory muscle weakness.
Limb onset: Weakness often starts distally and asymmetrically in one limb, then spreads (e.g., foot drop, hand weakness).
Respiratory failure: Due to diaphragmatic and intercostal muscle weakness, common cause of death.
Diagnosis:
Clinical diagnosis based on the presence of UMN and LMN signs in at least two body regions, with progression, and exclusion of other conditions.
EMG and nerve conduction studies (NCS): Show evidence of denervation (fibrillations, fasciculations) and reinnervation (large motor unit potentials) in multiple muscles, with normal sensory nerve conduction.
Medical Management:
Riluzole: Only drug shown to slow disease progression (by a few months).
Edaravone: May slow functional decline in some patients.
Symptomatic management: Baclofen/tizanidine for spasticity, botulinum toxin for sialorrhea, non-invasive ventilation (BiPAP/CPAP) for respiratory support, percutaneous endoscopic gastrostomy (PEG) tube for nutritional support.
Physical Therapy Treatment:
Focus on maintaining function, managing symptoms, and adapting to progressive weakness.
Early stages: Gentle, non-fatiguing strengthening exercises, active range of motion (AROM) and passive range of motion (PROM) to prevent contractures.
Middle stages: Provide assistive devices (canes, walkers, orthotics for foot drop), continue ROM, energy conservation techniques, educate on home modifications.
Late stages: Wheelchair mobility, pressure relief techniques, respiratory care (manual assisted cough, postural drainage), caregiver training for transfers and ADLs, communication strategies.
Avoid over-fatigue and muscle damage as this can exacerbate weakness.
Cerebellar Pathology
Key Manifestations: Cerebellar lesions primarily impact coordination, balance, and motor learning, without affecting primary muscle strength or sensation (unless secondary pathways are involved).
Asthenia: Generalized muscle weakness or fatigue, perceived as heavy limbs.
Asynergia (or Dyssynergia): Loss of ability to associate muscles together for complex movements; movements are executed in a component-by-component sequence rather than smoothly integrated (e.g., finger-to-nose test becomes a series of disjointed movements).
Delayed Reaction Time: Increased initiation time for voluntary movement, with prolonged movement execution.
Dysarthria: Motor speech disorder affecting articulation, often described as 'scanning speech' (slow, slurred, monotonous, broken into syllables).
Dysdiadochokinesia: Impaired ability to perform rapid alternating movements (e.g., pronation/supination of the forearm, tapping feet).
Dysmetria: Inability to accurately judge distance or range of movements. Can be hypometria (underestimation of distance, undershooting a target) or hypermetria (overestimation of distance, overshooting a target).
Gait Disorders: Ataxic patterns with postural instability, broad base of support (WBOS), staggering, and uncoordinated steps (resembles drunken gait).
Hypotonia: Reduced muscle tone (flaccidity), resulting in diminished resistance to passive movement and decreased DTRs (pendular reflexes).
Nystagmus: Rhythmic back-and-forth eye movement, often gaze-evoked, due to impaired control of eye muscles.
Rebound Phenomenon: Unable to cease forceful movements once resistance is suddenly removed (e.g., pushing arm against resistance, then resistance is removed, arm might fly back and hit patient).
Tremor: Involuntary oscillatory behavior due to alternate muscle group contractions; intention tremor is characteristic of cerebellar lesions, occurring during voluntary movement and worsening as the target is approached.
Differentiating from Basal Ganglia Pathology: While both affect movement, their manifestations are distinct:
Akinesia/Bradykinesia/Hypokinesia: Inability to start movement, slowness, and reduced amplitude of movement; associated with rigidity and fixed postures (e.g., Parkinson's), often exacerbated by dual-tasking.
Rigidity: Increased muscle tone that is constant throughout the range of motion (lead-pipe) or jerky (cogwheel), non-velocity-dependent.
Resting Tremor: Involuntary rhythmic oscillation occurring when the limb is at rest (e.g., pill-rolling tremor in PD).
Chorea: Rapid irregular, involuntary, jerky, unpredictable muscle movements that flow randomly across multiple joints (e.g., Huntington's disease).
Athetosis: Slow, writhing, involuntary movements, especially in distal extremities.
Dystonia: Sustained or repetitive muscle contractions resulting in twisting and repetitive movements or abnormal fixed postures.
Tics: Sudden, rapid, recurrent, non-rhythmic motor movement or vocalization (e.g., in Tourette's syndrome).
Stroke (CVA) Analysis
Definition: A sudden loss of neurological function caused by an interruption of blood flow to the brain, leading to cell death. It is a medical emergency.
Types:
Ischemic Stroke: Most common, accounting for 87% of CVAs, resulting from blocked blood flow in the brain (thrombus/embolism) leading to cerebral infarction. Often categorized by cause:
Thrombotic: Clot forms within an artery in the brain, often due to atherosclerosis.
Embolic: Clot travels from another part of the body (e.g., heart with A-fib) and lodges in a cerebral artery.
Lacunar: Small infarcts in deep brain structures (basal ganglia, thalamus, brainstem, internal capsule) due to occlusion of small penetrating arteries.
Hemorrhagic Stroke: Less common (13% of CVAs), results from a ruptured blood vessel, leading to bleeding into the brain tissue (intracerebral hemorrhage) or surrounding spaces (subarachnoid hemorrhage), causing direct tissue damage and increased intracranial pressure. More severe outcomes and higher mortality.
Transient Ischemic Attack (TIA): Temporary symptoms due to reduced blood supply, often described as a